Telephone-exchange system



I 7 Sheets-Sheet l K. M. FETZER ET AL Filed Oct. 10, 1924 Jan. 11 1,927;

TELEPHONE EXCHANGE SYSTEM 4 WMM Q WIR -wn www g Q W w. e A@ @www l .wf Wm 1 m y L f TELEPHONE EXCHANGE SYSTEM Filed oct. 1o, 1924 7 sheets-Sheet 2 /fIl/eY/i/a/v:

/fdf/ M ffzer /Vor/fm/i A /Vemw/ Jan. 11, 1927.

' 1,614,291 K. M. FETzl-:R ET AL v TELEPHONE EXCHANGE SYSTEM Filea'ot. 1o, 1924 'r sheetss'ee't s www. ,427;

Jan. 11, 1927.

Filed oct. 1o, 1924 Jan. 11,1927@ 1 A 1,614,291

` K. M. FETZER AL TELEPHONE EXCHANGE SYSTEM Filed oct. 1o, 1924 7 Sheng-sheer IIHIl 1,614,291 Jan. y l I K.- M. `FET-2ER AL TELEPHONE EXCHANGE SYSTEM Jan. v11, 1927. E I 1,614,291

.K. M. FETZER' ET AL. l

` TELEPHONE EXCHANGE SYSTEM Filed oct. 1o, i924 7 sheetsLshe-et v Il Irl I III I 5mm. CONTROL AND DISTRIBUTOR SEQUENCE CIRCUIT RECEIVER Afa/maf; 4. /Ve/re// /fdf/ M fe/Zer Patented Jan. 11, 1927.

TBS

KARL IVI. FETZER, OF RUTHRFGRD, AND NORIVIAEI A. NE'WELL, Ol LYNDHURST, NEW JERSEY, ASSGNBS EO 'WESTERN ELEC'ERC ClfPANY, lC'Z-LRATED, OF NEW YORK, ll'. Y., A GBJEOBATEGNQF IIEY YORK.

TELEEONE-EXCHAITGE SYSTEM.

Application tiled October l0, 1924. Serial No. 742,749.

This invention relates to improvements in telephone exchange systems, and especially to those systems employing what is known as straightforward trunking between switchboards or exchanges.v

lfn such systems, an A or outward operator receives an originating call and trunks it to a B or inward operator who may be located in the same or in a distant exchange.

An object of the' invention is to improve the operating eiiiciency of systems of this character.

In the patent to Fetzer No. 1,578,651

issued March 30, 1926, there is disclosed a system wherein the signaling between A and B Ioperators is controlled over a common signaling circuit and in which the B operators telephone set is automatically connected in a predetermined sequential order to the calling trunks.Y

In the system described, a line' lamp is provided at the B operators position for each incoming' trunk and when one of the trunks is seized atthe A operators position, for the purpose of initiating a call, a signal is transmitted over the oinmon signalingcircuit to cause the lamp associated with the lseized trunk to light and to connect the B operators telephone set to the trunk. lWhen the B operator extends the trunl by plugging it into a subscribers line, or another trunk, the lamp is extinguished and the operators telephone is disconnected. Nhen the A operator releases the trunk, another signal is transmitted over the common circuit to cause the lamp to relight as a disconnect signal whereupon, in the ordinary course of operation, the B operator will remove the trunk plug from the called line,` thus extinguishing the lamp and restoring the circuit to normal.

However, in case the A operator. after releasing the trunk. which causes a disconnect signal to be dispiayed at the B operators position, should again seize the same trunk for the purpose of initiating a second call before th B operator has `disconnected the trunlr from the first called line, a third signal is transmitted over the common circuit which maintains the previously lighted disconnect signal, which now acts a re-connect signal, and which also causes the operators telephone set, to be connected to the trunk in the regular sequential order, whereupon the signal is caused to iiash as before.

A feature of this invention, therefore, resides in the provision of means, in a system as before described, whereby a trunk disconnect signal at an inward or B operators extending to the B operators position and thetiming apparatus associated with the cord circuits for allowing the A operator to change cords without sending a disconnect signal to the B operator.

Fig. 3 shows the B operators position with a trunk circuitand controlling apparatus operating in conjunctionv with the common signaling circuit.

Fig. 4f shows the operators telephone sets and call sequence circuits for two B yoperators positions and the auxiliary apparatus therefor.

Fig. 5 shows a portion of the apparatus of the common signaling' circuit which cooperates -with the apparatus of Fig'. l.

Fig. y6 shows the switching mechanism and apparatus associated with the common signaling circuit located at an A operators position. Y

Fig. 7 shows the switching mechanism and apparatus associated with the common signaling circuit located at the B operators position which operates in synchronism with the apparatus at lthe A operators position.

General method of operation.

rThe straightforward trunl; line circuits are arranged to give complete switchhook supervision to the outward operator. The circuits are arranged to start machine ringing when the connection is established and to enable the outward operator to rering in order to recall a subscriber.

VThe trunk circuits disclosed herein are arranged to be used with a distributor signaling system, but the use of other signaling arrangements may be readily provided for.

The trunk lines terminate in the outward board in multiple jacks equipped with visual busy signals and at the inward board in a single cord and plug with associated lamp signal and team key.

The outward operator originating a call after securing connection with the calling subscriber by means ot the answering end of a cord circuit places the calling plugot' the cord circuit into the trunk ot an idle trunk line. This operation causes the busy signals to be displayed and lights the signal lamp at the inward end ot the trunk and also connects a tone signal to the trunk line, notifying the outward operator that the connection is being extended to the inward operators telephone set.

At the inward end of the trunk circuit, the inward operators telephone set is automatically connected in succession to trunk lines on which calls are waiting. llllien the operators telephone set is connected, the tone signal is disconnected from the trunk line and the outward operator then immediately passes the call. The inward operator comm plete-s the connection in the usual manner by placing the trunk plug into the jack of the subscribers line. The inward operators telephone set is disconnected from the trunk line either when the trunk plug is placed into the line jack of the called subscriber or by the operation ot a release key common to the position.

rlhe inward operator at a position adiacent to one in which. trunk lines terminate mayanswer on these trunk lines by operating the team key. The purpose ot this feature is to allow team work among the inward operators. The ad]acent operators telephone set is released troni a toll line in the same manner as that of the home operator.

The trunk lines are available for other connections as soon as released by the outward operator it the called subscribers receiver is 0n the switchhook. Provision is Inade for a delay ot 21/2 seconds before the disconnect signal is transinitted and the visual busy signal released.`r it the outward operator should disconnect while the recei ver of the called subscriber is ott the switchliook. The reason for this delay is to permit the outward operator to change cord circuits it necessary, .for example in case the .first cord circuits are detect-ive. The change if made within 21/2 seconds is elifected without giving a disconnect signal to the inward operator.

After the outward operator secures troni the calling subscriber the number of the wanted line, she places the calling plug P into an idle trunk i ack J. This completes the circuit ot relay 3 as tollowsz ground, battery, winding' et relay 2, 100, Winding ot' relay 1, 101, l), J, 102, winding o1' relay 3 to ground.

The operation ot' relay 3 completes the circuit ot relay e as follows: ground, contacts of relay 3, 105, contacts of relay 5, 106, contacts ot relay 13, 107, winding ot relay el, 108, contacts ot relay S, battery to ground.

Relay L1 operates and closes the circuit of relay 5 as follows: ground, battery. inner lett contacts of relay Il, 109, winding of relay 5, 110` contacts ot' relay 13, to ground. lllhen relay el operates it also connects ground to conductor 121 extending to the signal sequence circuit (Fig. 1) and causes this circuit to Jfunction to cause the transmission ot' a. current pulse over conductor 600 (Fig. 6) and 700 (Fig. 7) to operate relay 7 01 at the distant end of the trunk line as will be described later.

The operation ot relay 4e connects battery to the winding ot the busy signal 16 indicating that its associated. multiple jacks are busy. These signals are held operated zitter relay 41 releases as relay 5 also connects battery to the winding of the busy signals. The operation or' relay 4. also closes the circuit ot relay 7 as follows: ground, battery, left .inner contacts of relay 4, winding of relay 7 127, contacts ot relay 6 to ground. 'l'he operation of relay 5 opens the circuit which resulted in the operation ot' relay a, but this latter relay remains locked to ground under control ot relay 8 through its own Contact.

Relay 5 is locked to battery through one oit its own contacts and can only be released by the operation ot relay 13. IThe operation ot' relay 7 disconnects the grounded right hand winding of relay 10 from conductor 125 thereby removing the short circuit around the righthand winding of relay G.

ReturningI now to the operation of the signal sequence circuit, when ground was connected to the conductor 121, it caused the operation ot relay 17 (Fig. 1), a circuit tor which can be traced from ground, out-er right alternate contacts ot relay 1, conductor 121, winding of relay 17, normal contacts of relays 18 and 19, and the contacts of any other relays between relays 18 and 19, as shown by the broken line to battery and ground.

Relay 17 in operating connects ground at its alter ate contacts to energize relays 30 and 31 in an obvious circuit. Relay 3l in operating causes the energization ot' relays 501 and 502 (Fig. 5) in the tollowing circuit:

Gfround, outer right alternate contacts of relay 1, conductor 121, left alternate contacts of relay 31, conductor 32, right hand Winding of relay 501, conductor 503 and Winding ot relay 502 to battery.

Relay 502 in operating grounds the ST lead ext-ending through relay 601 to battery, Which relay energizes and in closing its al tornate contacts Completes a circuitt'or the operation of relay 602, which can be trac-ed from ground on the ST lead over contacts ot relays 601 and 603, through Winding of relay 602 to battery. i

Relay 602 in closing its contacts completes the circuit for the start magnet 604, which can be traced trom battery through the Winding ot magnet 604, alternate contacts of relay 602, segment 605 ot' the transmitter distributor TRANS, brush arm 606 and the grounded inner segment of the distributor.

Magnet 604 in attracting its armature releases brush arm 606, which starts revolving in a clockwise direction. l/Vhen the brush arm starts to revolve the outer brushes break contact with segment 611, thereby opening the normally closed circuit of relay 610, the energizing circuit tor which can be traced from battery over segment 609 ot the transmitting distributor, brush arm 606 and its brushes, segment- 611, lead 613, and the Winding of relay 610 to ground.

Vhen relay .610 deenergized, its armature opened its alternate or front contacts Y and caused relay 701 7) at the distant end of the line to release, Which relay is normally operated due to the normally operated condition of relay 610.

Relay 701 in releasing connects ground at its alternate contacte over lead 702 to segment 703 of the receiving distributor' REC, thereby causing release magnet 704 to attract its arma-ture and release brush arm 705, which at once starts to revolve in a clockwise direction in substantial synchronism With the transmitting distributor.

lVhen the brush arm 606 reaches segment 607 it connects battery standing on segment 609 to vlead 60S, thereby causing the reenergization ot' relay 610 in the, following circuit: battery, segment 609, brush arm 606, segment 607, lead 608, contacts of relay 501, leads 504 and 505 and the Winding ot relay 610 to ground.

Relay 610 in operating reconnects battery at its alternate contacts to lead 600, thereby causing relay 701 at the distant end to operate, which connects ground over lead 706 to segment 7 07 ot the receiving distributor. As before mention-ed, the transmitting and receiving distributors rotate in substantial synchronism andA` therefore, during the period the brush arm 606 ot the transmitter has its brushes in Contact with segment 607, brush arm 705 ot the receiving distributor Will bring its brushes rinto contact With segment 708, thereby completing a circuit for the operation of relay 709, which can be traced from battery 710, Winding of r'elay 7 09, segment 708, outer brushes of brush arm 705, segment 707, conductor 706 and normal contacts ot' relay 701 to ground.

lllhen relay 7 09 operates, it locks itself by means o1 its right Winding and inner armature contacts to ground on segment 711, over segment 712 and the inner brush-es of brush arm 705, which locking circuit will be maintained closed until the brush arm 705 leaves segment 711 near the completion ot the revolution.

1V hen relay 7 09 operated, it connected ground at its outer armature contacts to conductor 713, thereby causing the operation ot relays 7111, 715, 716 and 717 in an obvious circuit.

Relay 711L in operating prepares a circuit for the operation of relay 39 associated with the inner end ot' the conductor (Fig. 3), which circuit will be closed When the brush arm otv the receiving distributor bridges segments 718 and 719. The circuit thus completed can he traced from negative battery over conductor 720, normal contacts oi' relay 721, segment 718, outer brushes of brush arm 705, segment 719, outer normal contacts or relay 722, lower normal contacts of relay 7 23, lon'er normal contacts ot' relay 724, lower alternate contacts of relay 71st, upper normal contacts of relay 726, conductor 725 and lett hand Winding' of relay 39 to ground, which relay in operating locks itself at its right iand alternate contacts to battery.

t should be notedthat the windings of relay 39 are so connected that the negative locking battery aids the negative battery supplied through the left hand Winding whereby the relay remains operated after the operating pulse ceases, whereas a positive operating pulse would have momentarily operated the relay but it could not have locked as it Would have opposed the negative locking battery.

As none ot the other chainrelays (Fig. 5) Tvere operated by the seizure or' the trunk line, shown in Fig. 2, none oit the other four outer segments 614-., 615, 616 and 617 of the transmi.lt-ing` distributor will affect relay 610 and, therefore,- its armatures Will retractl as soon as the outer brushes of brush arm 606 leave segment 607 and Will remain in its retracted position until the brushes- 618, an obvious through the windino' ot' relay 603, left. alternate contacts ot relay G03, winding of relay 519 and lei't alternate contact or relay 601 to ground on the ST lead.

)relay 619 did not operate in this circuit, however, as its winding was shunt ld by ground on segment (S13 of the distributor, as previously nientioncd. )Viren the brush arn'i 60G, however, in completing its revolution inored oil so 'inent 613, this short circuit was reinoved iiroin relay 619, and, theretore, this relay operated in the circuit previously traced.

rlhe operation ot relay conipletes an energizing circuit for relay 3 which can be traced troni battery, winding oiu relay 3, conductor 122, right hand alternate contacts ot relay 3l, (Fig. 1), conductor 33, alternate contacts oi'i relay 619, conductor (520, alternate contacts ot relay 601 to ground on the S' lead, which is supplied at the alternate contacts oi? relay 502, (Fig. 5).

The operation el: relay 3 opens at its nornial contacts the holding circuit itor relay 4, which relay releases and rcn'ioves ground at its outer right alternate contacts Yl'roni lead 121, thereby causing the deenergization oi' relays 17, 501, 502, und 31. Relay 502 in releasing reinoves the ground troni the ST lead thereby causing the release ot' relays 601, (502, 603 and 019. 'lhe release of relay 602 opens the circuit tor the start magnet 604, which therefore, releases its armature, which takes up a position to stop the brush arin 606, when it has completed its revolution. All relays associated ith the transmittingdistributor are now in nornial position and in readiness to transmit another signal.

The release ot' relay 4 1), which removes the ground from conductor 121, prevents further transmission ot signals until further changes occur at the outward end of the trunk circuit.

rlhe operation ot' relay 39 (Fig. 3) at the inward end oic the trunlt completes the circuit of relay as follows: ground, battery, contacts ot relay 39, contacts of relay 40, 179, winding of relay 50, contacts o't' relay 56 to ground.

The operation ot relay 39 completes the circuit ot the signal lanip Q as "follows: ground, battery, contacts of relay 39, 170, contacts ol? relay 46, 172, contacts of relay 47, 174, contacts ot relay 43, 175, contacts of relay 47, 177, contacts of relay 46, 178, lainp Q to ground. rlhe lighting oli this lainp notifies the inward operator ot the call.

The operation ot relay 39 also completes the circuit or' relay 41 as follows: ground, battery, contacts ot relay 39, 170, contacts of relay 46, 172, 173, contacts of relay 47, 174, contacts of relay 43, 175, winding of relay 41 to ground. The operation of relay 41 connects tone to the tip and ring conductors 134 and A35 of the trunk, thus indicat-ing to the outward operator that the signal has been transmitted to the inward operators position.

The operation of relay 39 also coinpletes the circuit ol relay 42 as tollows: ground, battery, contacts oi relay 4G, 172, 39, 170, contacts of relay 173, contacts ot relay 47, 174, right hand winding` olf relay 42 to ground. The operation ot relay 42 connects ground troni relay (Fig. 4) and conductor 190 over conductor 139 to trie call sequence circuit which includes relay 72 thereby causing the connection or' the operators telephone set to the selected trunlr. rl`he operation ot relay 42 also transfers one terniinal ot its lett hand winding troni ground to conductor 190. rlhe reason ior this connection will be later explained.

rlhe o )eration ot relay 42 as above inentioned, closes the circuit ot' relay 72 as follows: ground, contacts of relay 70, 190, concontacts of relay 7G, 184, contacts of relay 75, 185, battery to ground.

lr hen there are no calls awaiting on other trunks ground is connected to relay as iollows: ground, contacts oli relay 71, alternate contacts of relay 72, 132, winding ot relay 43 to battery. 'lhe operation of relay 43 opens the. circuit or' relay 41, thereby releasing it, which disconnects the tone signal troni the tip and ring conductors notifying the outward operator that the inward operator is connected to the trunk and is in position to receive the order relay 41 at the saine tinie it connects the tip and ring conductors 134, 135 ot the trunk to conductors 136 and 137.

rlhe operation of relay 43 also connects the tip and ring or the No. 1 operators telephone set to conductors 136 and 137 thus completing a connection with the trunlr so the inward operator inay converse with the outward operator.

Relay 42 is slow in operating while relay 41 is slow in releasing. This combination insures that the tone signal is connected to the toll trunk for a sutl'icient length of tiine to give the 'full signals to the outward operator.

rlhe operation oi' relay r`i3 also disconnects continuousbattery troni the lainp Q and connectsI interrupted battery to the lainp as follows: ground, battery, contacts ot interrupter relay 33, 253, 201, contacts of relay 43, 176, contacts ot relay 47, 177, contacts of relay 40, 173, lainp Q, to ground.

This interrupted battery current causes the lamp to tlash at a certain (busy back) frequency indicating to the inward operator to which trunk circuit her telephone set is connected.

tacts ot relay 139, winding ot relay 72,'

The operation of relay 43 also' connects battery to the leit` handv Winding oli relay 42" 44 conipletes the circuit of relay 46 as fol.-`

lows :r ground, contacts of relay 44, 191,. 46, 192,. contacts or rela-y (58,. battery to ground. The operation of relay 46 'opens the circuit ot the lainp Q', closes the tip' conductor of the trunk and' disconnect-s battery from thev winding, of relay 42.. The release. of relay 42, disconnectsground troni conductor -189I extending to the call' sequence circuit, Fig. 4, and this in turn disconnects. ground troni conductor 182v causing the release of relay 43. The release of relay 48 disconnects the inward. operators telephone set from the trunk..

When. there are several calls waiting ona trunk lines terminating in one position and the operator adjacent to position is idle she niay answer oney of the Waiting calls by operating the teain key associated With the trunk line. rlhe teainl key individual toeach trunk:` is shown at X. The operation of this key completes the. circuit ot relay 47 as folloivs: ground, contacts oi' X, Winding ot relay 47, 1'7 2,. contacts of relay 46, 17 O, contacts or? relay 39, battery to ground.4

T he circuit ot' relay 48 is conipletedin parallel to that of relay 47 over/the'path just traced. `fWhen' relays 47 and 48`are opera-ted.' they ren-lain locked to ground through contacts of relay 48 to conductor 211. This ground.' is furnished` through release key 700 ot t-lieadjacent ope-rators position.

The operation of relay 48 alsoconnects the tip and ring and busy test lead ofV the adjacent or No. 2 operators telephone to the trunk. The operation of relay 47 connectsground tov conductor extending through contacts of' relay 70 and over conductor 258 to the. cal-l sequence circuit otl the adjacent or No. 2. operators position operating relay 712. Ground being connected in this inanner prevents the No., 2 operators telephone Y set being automatically connected to a trunk ing of relayl 84, interrupterf Z. to ground.. Relay 84 is intermittently' operated by inter'- rupter Z at a dililerent (pere1npto1y)v rate: than relay 88- and causes the lanrp circuit Q; to be interrupted over the following.' patlrz. ground, battery, contacts ot relay 84, 252, contacts of relay 70,. 251', contacts.' ofy relay 47, 177, contacts of rel-ay 46, 178-,.la1n.p: Q. toy grou-nd.

The. flashing of lamp at this pereinptory rate indicates to they No.. 1 operator.- that the. call has been answered by' another operator.

The operation of relay 47 alsol disconnects battery troni the Winding ot relay 41l and the auxiliary signal circuit and tron-r theivinding ot relay 42. rllieireleaseiofl relay 4-1 disconnects the tone signal: fronrthetrunfk line and the release oat'- relay42 disconnects` ground froml conductor 189 extending to the call; sequence circuit.

The adjacent operator. completes-11 the. con'- ne'ctioir in the usual inanner and connectsfthetrunk with a subscribers line', thereby op*-l erating relay 44y in the manner previously described..

'lille operation of relay 46- closes thev tip side otV the trunk circuit, extinguishes thev signalA lainp and disconnects batteryf from the windings of relays 47 andz 485 causing their release. Therelease of theserelays disconnects tlie inward operators telephone set at theV adjacent position troniV the trunkl line.

lVhen the connection is. completed tothe line of the called subscriber by any inward operator the sleeve relay' 44 connects: ground? to` operaterelays49 and 50; rllhe circuit of relay 49' is completed asl follows: ground', contacts of sleeve relay 44, 220,. contacts olli relay 62,. 228, contacts of relay 61., 229, contacts of relay 55, 231, contacts of relay 50, 232,. contacts of relay 49, Winding ot relay 49, 283,y contacts of relay 55, battery to ground.. The circuit of relay 50f is cornpletedz over the saine path as relayv 429.: except that its Winding is connectedi directly to battery instead: of through. the contacts. of relay 55. p

Relay 50. is slightly slow in operation andi does not open the circuit extending tofrelayy 49 until the latter relay has hadi time to operate and lock to ground through Vits OWIr contact.

The operation of relay 49 connects; ground tofconductor 222 which results in? the trans'- initter distributor 728 sending over conductor 727 signal impulses to.- the outwardl endf of the trunk to set up a conditiony in:V the` signa'll receiving circuit 621 of Fig'. 6l in eX- actly the same manner asthat previously' ole-v scribed in. connection Wit-hthev initiation of the trunk connection. It Will be5 assunnedV that the condition set up in the signal re'- ceiying circuit 621 of F ig. 6i causesnegative 120 volt battery to bey momentarily-v con'- nected'r to. conductor 125l extending through4 12in jack the right hand Winding or" relay 6 (Fig. 2) to ground thus causing this relay to operate when the receiving distributor' 622 bridges its segmentsV corresponding to 717, 179 of the distributor shown in detail in Fig. 7. Relay 6 in operating locks through its lett hand Winding and leit armature contact to battery at the inner lett alternate contact ot relay which relay i will l' e recalled Was operated and locked under control ol relay 13 at the time the trunk was seized.

lelay 3 is ot asurliciently high resistance so that relay 1 did not operate in series with it, and relay 2, when the plug Was inserted llhen relay 6 operates however, resistance A is connected in shunt with relay 3 thereby causing a su'ilicient change in the resistance or" the circuit of relay 1 to enable it to operate thereby lighting lanip L to indicate to the operator that the connection has been completed to the line ot the called subscriber but that all the receivers on the line are on their hooks.

Relay 6 in operating deencrgizes sloW-torelease relay 7 but this relay, due to its slow character, does not close its right normal contacts to connect relay 10 to lead 125 until after the 126 volt negativ pulse has ceased. l/Vhen relay 7 however is fully released relay 10 is connected to lead 125 and is in readiness to respond to any further iinpulses ot current connected thereto in the signal receiving circuit 621.

I Returning to the inward r nd or' the trunk: After relay operates, it is held operated by ground supplied through contacts of relay 44, until relay 51 has operated, and Will only be released by the operation of supervisory relay 62. rllhe operation ol relay 50 completes the circuit of relay 52 as follows: ground, contacts ol relay 44, 226, contacts of relay 52, 228, contacts ot relay 61, 229, contacts or' relay 55, 231, contacts of relay 50, Winding of relay 52, batt-ery to ground.

.Relay 52, in operating. connects a slow acting relay 59 to the alternate contacts ot relay 62. Relay 59 does not operate at this tin'ie, however, since relay 62 is not yet operated.

rlhe functions controlled by the operation of relays 52 and 49 Will be later described in connection With the flashing systeni.

1rl`he operation of relay 49 completes the circuit of relay as follows: ground, contacts of relay 49, 216, contacts ot relay 54,

Athrough a back contact of relay 61, the

purpose of which will be described later.

rennes1' 'l/Vhen the signal sent over the distributor signaling circuit has been transmitted to the A or outward position, Where it operates relay 6 etc., as previously described, a inornentary ground connection is Inade With conductor 224 When the transmitting distributor 728 completes its revolution in the saine manner that ground Was connected to conductor 53 to operate relay 8 as previously described. rlhis ground on conductor 224 operates relay ior a short interval ot time. The operation ot relay 55 Will release relay 49 and leave it in a position to transinit another signal tothe signal storing cir cuit.

The release of relay 49 causesthe operation of relay 54 in the manner previously described. The operation of relay 54 coinpletes the :following circuit: ground, contacts of relay 52, 204, contacts ot' relay 54, 203, contacts ont relay 60, 205, lett hand Winding or relay 56, 206, contacts of relay 57,207, pick up interruptor 506 to battery. Relay 56 locirs up through its second Winding to battery through contacts oi relays 39 and 57.

The oper tion o' relay 56 prepares a circuit for operating relay 57 when relay 52 is released and also connects the Winding ot relay 58 to ground through interrupter 600. llhe operation ot relay 56 also opens the cir-- cuit of relay 60 causing it to release, the purpose or which ivill be described later.

The circuit of relay 5S is completed as follows: ground, interruptor 600, contacts ot relay 51, 226, contacts of relay 56, 227 Winding ot relay 58, battery to ground. The op eration of relay 5S connects ringing current to the tip and ring conductors oi the outgoing end of the trunk to the called subscribers line.

Ringing current Will be applied to the subscriberls line in tivo second intervals, such intervals being regulated by the conoH inutator of interrupter 660.

lNhen the called part-y removes his receiver the supervisory relay 62 operates. rllhe operation ot lthis relay opens the circuit ol relay 50 Which in turn opens the circuit ol relay 52. Relay 59 operates momentarily but has no etl'ect upon the circuit. rl"he release oi relay 52 causes the operation or relay 57 by completing ground tothe following path: ground, contacts of relay 44, 220,' contacts ot relay 62, 219 contacts of relay 52, contacts orp relay 5, contacts of relay 56, lett hand vinding ot relay V57, contacts ol relay 39, battery to ground. Relay 57 locks through its right hand Winding to ground through the baclr contact ot relay 40, and

its operation causes the release of relay 56.

The release of relay 56 disconnects relay 58 from the ringing interruptor and opens the operating circuit for relay 57. The release of relay 56 causes relay 66 to becorne operated again. Y

I he release of relay 52 connects ground to relay 61 as follows: ground, contacts of relay 44, 220, contacts of relay 62, 219, contacts of relay 52, contacts of relay 54, 211, contacts of relay 29, 210, winding of relay 61, 234, contacts of relay 55, battery to ground.

The operation of relay 61 connects ground to conductors 222 and 223 exten-ding to the signal control circuit (Fig. 7) and establishes a condition which results in the transmitting distributor 72S sending over conductor 727 two current pulses which cause the receiving distributor 622 and the signal receiving circuit 621 to connect a momentary pulse of positive polarity 12,0 volt current to conductor which, due to the connec tion of the windings of relay 6, causes this relay to release. r1`he reason for this is that the locking current flowing in the left winding of relay 6 is of negative polarity and as the connection of the right hand winding to conductor 125 is such that a negative pulse incoming thereover will aid the locking circuit, then a positive pulse coming in over the conductor 125 will oppose the effect of locking circuit and cause the relay to release.

The release of relay 6 removes the shunt from relay 3 and thereby increases the resistance in the circuit of relay 1 to such a point that it will not hold operated. The release of relay 1 opens the circuit of lamp L which becomes darlr and signifies to the A operator that the called subscriber has responded.

The operation of relay 61 also releases relays 53 and 54.

Vlhen the receiver of the called subscriber is removed and the signal indicating that -fact has been transmitted over the distributor signaling circuit, a short impulse of lground is applied to conductor 224 at the transmitting distributor circuit, in the saine v,manner as previously described in connec- 'the signal storing circuit.

Should the called subscriber replace the receiver on the switclihook before the c0nnection is talren down, the outward operator may recall him if desired by ringing on the circuit in the usual manner.

"When the outward operator re-rings, the ringing current flowing over conductors 'and 131 passes through the winding of relay 11 which is in series with condenser R and retardation coil C.

The ringing current operates relay 11 `which in turn completes the circuit of relay 12 as follows: ground, contacts of relay 11, 123, winding of relay 12, 124, contacts of relay 4, battery to ground.

lVhen relay 12 operates it locks to ground through contacts of relay 3. When the operator ceases ringing, relay 11 releases and closes the circuit of relay 4 as follows: ground, contacts of relay 11, contacts of relay 12, contacts of relay 13, 107, winding ot' relay 4, 108, contacts of relay 8, battery to ground. Relay 4 locks up again over its right hand contacts to battery at relay 8.

rillie operation of relay 4 releases relay 12 3y disconnecting battery from its winding, and also connects ground over conductor 121 to the signal storing circuit.

ln order to make the most efficient use of the distributor shown in Figs. 6 and 7, the same signal combination is used for ringing as was used to light the lamp Q when the call was intitiated, therefore the re-ring impulse is received at the inward end of the trani.; as a second impulse of negative 120 voit battery current over conductor 125. YWhen this second impulse of negative 120 volt current is transmitted over conductor relays 39 and 60 are already operated which permits the operation of relay 40 which locks up through its left hand winding over the following path: ground, contacts of relay 60, 181, winding of relay 40, contacts of relay 40, contacts ot relay 39, battery to ground.

T he operation of relay 40 opens the circuit of and causes the release of relay 57 and completes the circuit of relay 56 as follows: ground, contacts of relay 40, 203, contacts of relay 60, 205, winding of relay 5G, 206, contacts of relay 57, 207, interrupter 500 to ground.

The operation of relay 56 connects the ringing control lead to the winding of relay 58 causing it to operate as previously described. The operation of relay 56 also opens the circuit of and causes the release of relay 60, which in turn opens the circuit of and causes the release of relay 40.

The operation of relay 58 connects ringing current to the trunk and if the `called subscribers receiver is on the switchliool, the ringing' continues until the receiver is removed from the hook or until the connection is released.

lf the called subscribers receiver is oil the switchhook the operation of relay 58 will release relay 62 which will allow relays 49 and 50 to be operated from ground through the contacts of relay 44 as previously described. The operation of relay 49 will connect ground to conductor 222 to transmit a signal to the outward position where it will light lamp L for a short period. This signal is transmitted in exactly the same manner as previously described. However, when relay 58 releases on the iirst break of interrupter 600 and relay 62 operates relay 61 operates to transmit a signal to the outward position which extinguishes lamp L thus indicating that the receiver is oil' the hook. rEhe transmission ot this signal is the same as has been previously described. The operation ot relay 62 causes the operation ot relay 57 by closing the following path: ground, contacts ot relay 229, contacts ot relay (l2, 219, contacts ot relay 52, contacts ot relay 211, contacts of relay 56, 212, lett hand Winding ot relay 57, cont cts ot relay 39, battery to ground. rlhe operation ot relay 57 opens the circuit ot relay 513 Which upon restoring disconnects the ringing control conductor lfroin the Winding ot' relay 58 thus causing ringing current to be discontinued.

lllhen the ringing signal which Was established in the signal storing circuit by the ground applied to conductor 121 has been transmitted over the distributor' signaling circuit, an impulse ot ground is 'furnished from the signal circuit to the outward trank circuit over conductor 122 as has been previously described, resulting in the operation ot' relay S, and in turn the release ol:l relay 4. The release ot relay 4 removes ground trom conductor 121 and prevents any more signals being transmitted to the signal storing circuit until a further change has been made in the outward trunk ci cuit When the called subscriber flashes, that is moves his switchlioolr up and down to attract the fr operators attention, the irst downward movement releases relay G2. Relay 62 in releasing closes at its back Contact a parallel circuit tor the operation ot relays and 49 which can be traced troni ground at the inner alternate contact ot relay 44 conducto-r 220, contact ot relay 62, 228, onter normal contacts oi* relay 61, 229, right normal contacts ot relay 55, 231, then the circuit branches to the right through the right hand contacts and Winding ot relay 50 to battery, and to the lett through the lett hand normal contact ot relay 50 and the right hand normal contact, the Winding ot relay 49 and the inner lett hand Contact ot relay to battery.

Relay 50 in operating completes an energizing circuit for relay 52 which can be traced trom battery, Winding of 52, left alternate contact ot relay 5G, 231, right normal contacts oi relay 55, 229, outer right contacts ot relay 6l, 228, normal contacts ot relay G2, 220, and alternate contacts of relay 44 to ground.

Relay 50 also locks iteelt over its right alternate contact, 239, normal contact ot relay 51 and ground on conductor 229 as previously described.

Relay 49 in operating connects ground at its inner lett armature contact to conductor 216 thereby causing the operation ot' relay 53 in a circuit which can be traced over the inner right normal contacts ot relay 54, 215, Winding ot relay 58, conductor 170, and the alternate contact ot relay 39 to battery.

Relay 49 also connects to ground at its middle lett contact and conductor 222 which extends to the signal control circuit ot Fig. 7, thereby setting up a condition as previously describedwhich will cause the transmitting distributor 72S to transmit a single pulse over conductor 727 to the out-Ward end ot' the trunlr to there cause a. pulse of negatire 120 volt current to be connected to conduct-or 125 which will cause'lamp L to again light, as before described When the called line was plugged into. lt the called subscriber should not again release the switchhoolr lamp L would remain lighted as an indication that the called subscriber has hung up.

litter the transmitting distributor 7 28 has sent out the signal pulse above mentioned a `=`momentary ground is applied to conductor l as previously described which causes rea` to energize for a sutlicient period to relay 49 to release which relay Was Hed under control oi.l relay 55. llVhen relay releasesJ it permits the operation or relay et in series with relay 53 by removing the :hunt trom around relay 54. The energizing circuit ot these two relays, 53 and 54, can now be traced trom battery, contact of relay 39, 17 O, Winding and alternate contact of i y 53, 214, Winding ot relay 54, 213, and to ground at tbe contact ol relay 61.

pc loe 9 Jew, it' the subscriber quickly raises his switchboolr and lepresses it again the tollowing occurs: l

lVben the switclihoolr is raised supervisory relay G2 operates which in turn releases relay 50 and energizes relay 59, the circuit ot ,nich can be traced troni battery Winding ot' relay 59, 221, right alternate contacts oit relay 52, which Vrelay is slow to release, 219, actuated contacts ot relay 62, 220 and to ground over contacts of relay 44.

lrlelays 50 and 52 are slon7 to release and will hold operated during the flashing interval.

llhen the svvitchhoolr is once more depressed relay 62 deenergizes which again energizes relay 50 which in turn againlocks up under control of relay 62.

The release of relay 62 also operates relay 49 which again transmits a pulse of current over the signaling circuit which results in the application of a second pulse of negative 120 volt circuit to conductor 125 Which causes relay 1G, which was connected to conductor 125 When relay 7 released after the iirst pulse to operate. Relay 10, due to the connection ot its windings, locks up at its lettcoiitacts to negative battery, this holding circuit being completed at the alternate contacts ot' relay 8.

ylibe operation ot relay 10 transfers the reftance circuit for operating relay 1 troni steady ground at the normal contact ot relay 10 to ground in series With flash-` ing;interrupter1, thereby flashing the lamp. L, Whichfliasliing continues under control ot thev interruptor until the called subscriber stops working his switchbool.

lil/Then relay t9 operated at this time, due to the operated condition oli'. relayr 54, it caused the operation ot relay 51 the circuit of Which can be trac-ed from ground, inner left contact of relay. -921(5,.inner right alvternate contact ot relay 51, normal contact enengizes relay. 55 Which causes the release ot rela-y 4:9. l

Due tothe sloivcharacter ot. relays 52. and

59,. further flashing byA the subscriber will;

not. cause these relays. to= release and, as relay 5t) is locked up independentot relay 62, relay lll-cannot be. reenergized4 to cause the transmission' ot any further signals. Vllith relay 52 operatedthe release ot:v relay'52 can.- not operate relay 61 to cause a signalA to be transmittedto the outward. end of the trunk to: indicate that. the receiver of the called.`

subscriber is `olf the, sivitchhool.

W'hen the called subscriberstops flashing andv allows his receiver to remainv otl' the sivitchhoolnrelay 62. energizes and remains energized, so long as the receiver. is ott the switchhoolr.. VJhen relay 52 linally releases ground is connected. to theWindingotl relay 61 and a signal is transmitted over the distributor circuit similar to theA signal which indicates that the called subscriber has an.- sivered. outward` end ot the trunl; line'releasesthe flashing relays and eXt-inguishes lamp L thereby indicating that the receiver of the called subscriber is oil the switchhoolr.

rllhe energizing circuit for relay 61 can be traced from battery, outer lett normal contact of; relay 55, Winding ot relay 61,210, outer lelt. normal contacts ot relay 49, 211, left. alternate Contact oit-relay 5/1, rightv normaly contacts of relay 52, 219, alternate contacts ot relay 62,. 220 and contact ot relay fiel to ground.

lt the called. subscriber stops tlashingand their replaces the receiver on the switchhook then relay 62 releaseswhich Will release relay: but relay 52 will 'remain operated. Under these conditions, ground will be connectedi tothe Winding of relay '61 at the This' signal' when received at the back contacts ot relay 59.in.thefollowing1 circuit: ground, normal contacts of, relay 59, right alternate contacts ofrelay. 5l218y lett alternate contacts of relay 511,211,0uter lett normal contacts oly relay 49, Windingof relay. 61, 23st and contacts of relay 55 to` battery. Relay 61 in ope 'ating connects. ground. to leads 222 andI 223thereby causing'1 a. sig.- nal to-be transmitted as before to extinguish lamp L.; JHowever as soon as this signal isv transi'nitted due to the momentary'operation ot` relay 55, relays 61, 53, 50 andl are released Whereupon relay 49 Will beenergized. and a second. signal in'nnediately-set up. and transmitted to the outward. positionv to lightlainp L to indicate that the receiver of the called subscriber is on the swtchhook.

vl'lhen the outward operatork disconnects 'from the trunk extending to the line of` the called subscriber relay 3 is released. It the called subscriber has replacedy his` receiverl and relay is operated and relays- 7 and l released then the release; of. relay 3 `closes the ycircunit otl relay 13- as follows: ground contacts ot relay 3, 113, contacts ofrelayl-, 11.11, contacts 'of relay el, 115,.contacts ot'- relayt' 9 r, winding ot relay 1o, contact-sf of relay 8 battery to ground. The operationof relay 13 opens the circuit of relay. 5f and connects4 ground to the signal storing circuit over, conductors 120 and 121, causing,` the disconnect signal tobesent to the out-Wardend of the." trunk. This signal is received at the. inward endl or the trunk circuit as an impulse` ot positive 120 volt current over conductor. 225 which releases relay 39.: The release of. this-.relay completes the circuit, ot relay` 6.3; as. follows: ground, battery, contacts of. rez-- lay 39, 2.510, contacts of relay 6 3, Winding ot relay 63, contacts of relay 421 toground.. The operation of relay.v 63.2 completes the cir-- cuit ot' lamp C), astollows: ground, battery,I contacts or' relay 63, 19-1, contacts' of relay,v 46, 178, lamp Q to ground.. Relay 39=also releases 60.

rl`he` lighting of this lainp-servesito give a disconnect signal to the inward operator; Vhen relay 63 operates, it locks to battery through its own contacts and transfers; the Winding of relay L16 from battery through t le contacts ot relay 631 to battery through contacts ot relay 39. Theoperation ofrelay 63 alsoI opens the busy test leadf' extending from the tipv of the plug to the operators'A telephone set.

il? hen the disconnect signal is set up'l by the signal storing circuit at theoutward? end and is transmitted tothe distant' or: inward end of the trunk over thedistributor* signal system, aground impulse is reeeiyed from the signal storing circuit over conductor 122, resulting in: the operation of relayl 8 andv the consequent releaseof relay 13. The release of relay 13 disconnectsgground from conductors 120: and 121 andprevents-1 SLO any further signals being transmitted to the signal storing circuit until 'further changes have been inade in the outward trunk circuit.

After the inward operator receives the disconnect signal she removes trie plug troni the jack of the called line causing the release or relay its which in turn causes the release of relays 63 and e6, leaving the inward end of the trunk circuit in its norinal position to receive another call.

lf the inward operator is slow in taking down the connection the outward operator inay select the trunl; line rer another call beiore the connection or the lirst call is taken down.

vvlhen the out vard operator places the plug ol the cord circuit into the trunk jack, a signal is transmitted over the signaling circuit which is received the inward end of the trunlr as an impulse olf negative 120 volt battery over conductor 225. This iinpulse causes relay 89 to operate and lock up as previously described. ylie operation ot' this relay releases relay e6 and operates relays 60, l1 and and maintains the signal lamp Q lighted.

The circuit operates as previously described and the telephone set oi' the inward onerator l is cennected to the trunlr line as soon as the operator is l'ree to receive the call whereupon the sienal lanip Q is caused to i'lash before. lhe inward operator, however7 cannot release her telephone set troni the line until she disconnects the trunk line iiroin the subscriber-s line by withdrawing` the plug iircin the jack or unless she operates the emergency release ltey to be later described. 'lliis withdrawal releases relay which in turn releases relay 68. rEhe release ot relay restores the operators busy test lead to the tip of the plug and connects battery to the winding et relay Alti. The inward operator then connects the trunk line to the wanted line and releases her telephone set as previously described.

A release key 700 cominon to each operators position is provided to enable the inward operator to release lier telephone set 'from a trunl; if desired without requiring lier to plug the trunk into an outgoing subscribers line jack. This circuit is coinnien to all of the trunk circuits to which an operators telephone set niay oe connected.

The release key ZOO is non-locking and when operated removes ground from conductor 225 and connects ground through the back contacts oi relay Z7 and the winding of relay 78 over conductor 198 extending to the armature ot relay a2. lelay l2 being already energized in a circuit including its right hand winding, a circuit is thus conipleted through the left hand winding ot this relay to battery over the inner right alternate contacts ot relay a3, iniddle norinal contacts ot relay l?, conductor 172, inner right normal contacts of relay 26, 171, 170 and contacts of relay o9.

Due to the directional connection et the two windings oi relay L12 the completion of the circuit through the lett hand winding will cause this relay to release. rlhe release ot' relay 4t2 disconnects ground troni conductor 189 extending to the call sequence circuit thereby cz using relay to release. Relay .72 in releasing disconnects ground troni conductor 182 thus releasing relay i3 which disconnects the operators telephone set troni theJ trunk line. The release oi relay a2 also disconnects conductor 196 troni battery, which was supplied at the left alternate contacts or" this relay.

Relay 7S operated in series with the lett hand winding of relay l2 but releases when relay l2 releases. lVhen relay 78 operates it connects ground at its contacts to cause the operation ot relay 79 which relay in turn prepares a circuit tor the operation et relay Y? which can be traced trein battery7 winding of relay 79, alternate contacts of relay T conductor 19?, winding of relay 77, conductor 199 and lett hand contacts ot release key 700 to ground. Relay 77, however, does not operate at this tiine as it is shunted by ground at the alternate contacts of relay 78. lV hen relay 78 releases upon the release of relay l2 it reinoves the ground which previously shunted relay T7 and this relay then operates in the previously described circuit in series with relay 79. rlhe operation of relay i? renieves ground troni conductor 196 thus preventing incre than one trunk line releasing at once trein the operators telephone set even though the coinnion re- Ilease lteyhshould be held operated. Relays 9 and i l will be held operated as long as release lrey 700 is operated.

Delay feature to permit changing cords.

Should the outward operator disconnect bei'ore the called subscriber has hung up,

for the purpose ot' changing cords, for eX- Y ainple, there will be a delay of about 21/2 seconds betere. the disconnect signal to the inward operator is transmitted, and theretore the trunl; will be guarded at the outgoing end for this short interval vthus preventing ancther operator troni seizing the trunk during the changing operation. rlhis delay interval is accomplished by means of a series or chain ci slow release relays. rllhese relays are coniinon to a group oit iiiteen trunks.

if the outward operator should reconnect CII reaagsea 7 -fis operated at thetime relay 3 is released. lVhen the A operatordisconnects relay 3 releases which in turn releases relay 4.

lVith relay 7 operated the release ot relays 3 and 4 causes the operation of relay 14 the circuit for which can he traced from battery, winding of relay 14, 116, inner right alternate contacts of relay 7, 115,outer left normalcontacts of relay 4, outer left alternate contacts of relay 5, 113, 'and normal contacts of relay 3 to ground.

Relay 13 does not operate to ground conductor 121, thereby sending a signal pulse to the inward end to light the lamp Q as a. disconnect signal, until the timing circuit causes ground to Abe connected kto conductor 118, `unless the called subscriber should disconnect inthe meantime. It this should happen relay 6 operates' from negative 120 volt'current impulse received over conductor 125 causing relay 7 to release. Relay 13 then immediately operates on ground at the normal contacts ot relay 3 and causes the disconnect signal Vto be transmitted as pre Viously described.

The operation of relay 14 completes the circuit o1' relay 2O over conductor 117. The operationof relay 20 completes the circuit ot 'relay 21 which locks to ground through bach contact of relay 24 and front contact ot'relay 20. The operation of relay 2O also closes the circuit of stepping magnet 22 as liollowsrground, contacts of relay 20, 151, contacts of relay 23, 152, winding of magnet 22, interrupter contacts of kmagnet 22, resistance 400, lbattery to ground. The operation of the switch continues until relay 23 has its circuit completed which is when the wiper associated with the bank contacts O engages ground. This circuit at this time will be as follows: ground, battery winding ot' vrelay 23, O, 119, contacts o'l relay 14, to ground. The operation of relay 23 breaks the rcircuit of the stepping magnet 22 causing the switch to come to rest with the wipers resting on contactsvof the equipment associated with the trunl jack J. The operation of relay 23 completes the circuit ot' relay 24 as ollowsrground, contacts of relay 20, 151, contacts of relay 23, 156, contacts or" relay 24, contacts of relay 29, con tacts of relay 28, contacts ot relay 27, contacts of relay 25, 158, winding of relay 24, battery to ground.

The operation ot'rrelay 24 opens the circuit ot relay 21. Relay 21 in releasing connects battery to one side of the windings of relays 26, 29, 28, 27 and 25.

The operation of relay 24 causes the circuit'ot relay 25 to be completed as follows: ground, contacts of relay 20, 151, contactsfot relay 23, 156,' contacts of relays 24, y157, winding ot relay 25, to battery through the contacts ot relay 21. The operation'ot relay 25 opens the circuit of relay 24, but the y circuit of relay 25 remains closed. This cembinationallows the circuit of relay 27 to be completed as follows: ground, contacts ot relay 20, 151, contacts otrelay 23, 156, contacts ot' relay 24, 159, contacts of relay 25, 160, windingot' relay 27 to battery through the contacts of relay 2 1.

The operation et relay v27 opens lthe circu'it'o vrelay 25, -allowing it to restore. The

operation of r'relay .27 and the restoration` of relay cause ythe circuit of relay 28 to be closed as follows: ground, contacts of relay 2G, 151,centacts et relay 23, 156, contacts of relay 24, 159, contacts of relay 25, contacts lof relay 27, 161, winding or relay 28, to battery through the contacts of Yrelay 21.

The operation of Yrelay .28, opens the circuit oi" relay 27, allowing it to restore. The operation ot' 4relay 28, and the restoration ot relay vallows the circuit of relay 29 to be closed as follows: ground, contacts of relay 20, 151, contacts otl relay 23, 156, contacts ot relay 24, 159, contacts of relay 25, contacts ot relay 27, contacts of relay y28, 162, winding of relay 29, to battery through the contacts et relay 21.

rlie operation ot relay 29 opens the circuit oin reiay 28 causing 'it to restore, ithe restoration oit' relay l28 and the operation of relay A'cause Ithe circuit otl relay 261to 1rse-closed as follows: ground, contactsof reiay 20, 151, contacts of relay 23, v156, -contacts ot' relay .24, 159, contacts of relay 25, contacts ofrelay 27, contacts of relay 28, contacts of relay 29, .163, winding'of relay 26 `to battery fthrough the contacts of relay 21.

it this time tlie only relays in the timing circuit operated are relays 26, 23 and 26, with thiscombination 'the circuit of relay -13 is completed as follows: ground, contacts ot relay 20,1151, contacts ot relay 23, 156, contacts Aot' "relay 24, 159, vcontacts o1 relay 25, 27,28, 29, 1,64, contacts oi' `relay 26, 165, bank contacts 1T ot' the switch, 118, contacts ot relay 14, 112, winding of relay 13, to battery vthrcfugh vthe contacts of relay 8.

The operation of relay 13 opens the cir-' cuit-ot relay 5 and the release ot this relay opens ythe circuitsotl relays 7 and 14. rihe release of relay 14 'removes ground from conductors 117 and `119 causing the release ot relays 20, 23 and k26. l f

ln many instances the timing circuit will be released by the trunlr circuit before the timing opera-tion is complete. "vi'vhen this happens'the circuit/restores to normalunless ground is-connected yto conductors 117 and 119 by some other trunlr circuit.l 'In the latter case the switch will Vhunt for the other circuit :and when it is found will start the `timing operation over again.

.The :tact that relay 21 is operated durlltl ing the hunting period insures that any of the relays in the chain which might have been operated at the beginning of the hunting period will release and the full time interval will be obtained in each case,

@all seguano@ circuit.

rlhe call sequence circuit is arranged to connect an operations telephone set in suc cessiye order to the trunk lines terminating at her position on which calls are waiting. 1t is evident that in a group of trunk lines on which calls are originated independently, that call waiting signals may be received at a speed faster than can be handled by the inward operator and that some means is necessary to store up these calls and connect them to the operators telephone set in regular order.

For simplicity, the call sequence circuit, as illustrated, shows relays for three trunks only at one operator-s position.

Relays 72, 73 and 74 are operated by ground connected to their windings over conductors individual to the respective trunk lines. The battery for relays 72, 73 and 74 is supplied through the back contacts of relays 76 and 75 arranged in series. The battery supply for relays 72, 73, 74 is furnished through relay 75 which is numerically the highest trunk in the group.

Relays 7 5 and 76 are operated by ground connections received through the series of relays 72, 73 and 74 of numerically lower trunks. f

For the purpose of illustration we will assume that calls are originated simultaneously on trunks, 1, 2 and 15. Under these conditions there will be a ground placed on each 189 conductor extending from trunks l, 2 and 15. These ground connections operate relays 72, 73 and 74. The operation of relay 72 connects ground over conductor 182 to number 1 trunk circuit, but the operation of relays 73 and 74 at this time does not change the circuit conditions so long as relay 72 is operated. rllhe operation of relay 72 completes the circuit of relay 43 as follows: ground, contacts of relay 71, contacts of relay 72, conductor 182, winding of relay 43, battery to ground. The operation of relay 43 connects the operators telephone set to trunk number 1.

llfhen relay 72 is released which will be after the operator at the inward position completes the connection then relay 76 is operated over the following path: ground, contacts of relay 71, contacts of relay 72, contacts of relay 73 winding of relay 76, battery to ground. The operation of relay 76 completes the circuit of relay 43 of No. 2 trunk and connects the operators telephone set to that particular trunk.

After the connection has been established over No. 2 trunk, relay 73 is released thereby allowino` the operation of relay 75 byV the following path z ground, contacts of relay 7l, contacts of relay 72, contacts of relay 73, contacts of relay 74, 186, winding of relay 75, battery to ground. The operation of relay 75 completes the circuit of relay 43 of trunk No. 15, thereby connecting the operator-5s telephone set to that trunk.

After the establishment of the connection the operators telephone set is disconnected from trunk No.

rlhe operation of relay 75 which is the highest numbered trunk of this series breaks the battery supply extending to the windings of all the relays 72, 73, 74, etc., in the series. This prevents their operation in case a call should originate on one or more of the other' lower numbered trunks in the group. TWhen a connection has been established between the trunk and the called line, or the release key 700 is operated, as previously described, ground is removed from conductor 189 and this releases relay 74, which in turn releases relay 75.

Relay 72, 73 and 74 are slow to release their armatures and consequently there is an interval of time between the release of each relay from 72, 73, 74, etc., to its respective relay 76, 75, etc. By means of this time interval the call sequence circuit is made to operate in the regular order from the first toward the last trunk until all the signals of the higher numbered trunk lines have been transmitted. After this the sequence circuit returns to its normal starting position and is ready to repeat the operation.

Emergency transfer circuit.

The emergency transfer circuit is common to all of the inward trunks terminating at one inward operators position. This circuit allows the inward operator to answer manually on the trunk lines terminating at her position by operating the team key X associated with each trunk. rlhis feature will he necessary in case of trouble in the call sequence circuit. This circuit is operated by means of the emergency transfer key 729 which, when operated, connects ground to the windings of relays 70 and 80. The operation of relay 7() disconnects ground from conductor 190 thereby preventing operation of the call sequence circuit and opens the conductor 257 extending to the call sequence circuit at the adjacent position and also transfers conductor 211 from the position release key at the adjacent position to the one at the home position. The operation of this relay also transfers conductor 251 extending to interrupted battery at peremptory frequency to one corresponding to a lnisy hack frequency.

The operation ot' relay 8O transfers conductors 142, 143 and 254 common to the toll line from conductors extending to the adjacent operators telephone set and connects them to the home position telephone set.

VJ hat is claimed y:

l. ln a telephone exchange system a trunk line terminating atan operators position, a signal at said position associated with said trunk line, means for displaying'I said signal toindicate the seizure of said trunk line at its outward end, a telephone set at said operators position and means for automatically connecting said telephone set to said trunk line when said trunk is seized, means for automatically retiring said signal and for disconnecting said telephone set when said calling trunk is connected to a called line, means for re-displaying said signal when said trunk line is released at its outward end and means 'for maintaining the display of said signal and t'or re-connecting said telephone set when said trunk line is aga-in seized' at the' outward end before it is disconnected' from said called line.

2. 'En a telephone exchange system, the combination of an A operators position and a B operators position, trunk lines extending from theA A operators position to the. B operators position, a plurality of cord circuits at the A operators position arrangedk for connection with said trunk linesa telephone, set and a signal associated with each saidv trunk line at said B operators position, a signalling path common to said trunks extending between the A and B operators positions, means controlled over said common signalling Apath when one of said cord circuits is connected with one of said trunks tor operating said signal and for connecting the operators telephone set to said trunk, an outgoing line terminating at said B' position, means for connecting said trunk to said outgoing line, means responsive' to the connection of said trunk and said outgoing line for retiring said signal and' disconnectingsaid telephone set, means for causing said signal to be operated when said cord circuit is disconnected from said trunk and means for maintaining said signalv operated and tor causing` said telephone set to bel reconnectec` to said trunk line in case the same or another cord circuit is connected with said trunk at the A position Vbefore said trunk is disconnected from said outgoing line.

3. In a telephone exchange system, the combination of an A operators position, a B operators position, a trunk line eX- tending between said positions and terminating at the A operators position in a trunk jack and at the B operators position in a plug, a subscriber-s line at the B operators position terminating in a jack for connection with said plug, an operators telephone set at said B position, a signal associated with said plug, a plurality of cord circuits at the A operators` position arranged to be connected with said trunk jack, means for causing the operation of said signal and for connecting said telephone set to the trunk when connection is made with the trunk jack by means ot one of said cord circuits, means operated when the plug is placed into the jackV of subscribers line for restoring the signal and for disconnecting said operators telephone set, means for causing the re-operation of the signal when the A operator disconnects said one cord circuit from the trunk jack and means tor maintaining said signal operated and for connecting said operators telephone to said trunk in case'said A operator again connects a cordy circuit therewith beterev thev B operator disconnects the trunk plug from the jack of the subscribers line. y

4. In a telephone exchange system, the combination of an A operators position, a B operators position, trunk linesA extending between said positions, means at the B operators position for connecting said trunks to outgoing lines, a pluralityv of connecting circuits at theA A operators position forconnection with said trunk lines,Y an individual signal for each of said Ytrunk lines and an operators telephone set associated with said trunk vlines at the B 0perators position, a signalling circuit. oominon to said trunks extending betweenI said positions, means controlled over said common signalling circuit when a connection is" made with one of said trunks at the A operators position for causingv the operation of the signal and for connecting the operators telephone setto said trunk, means controlled at the B operators position for disconnect-l ing the signal andfordisconnecting theoperatorsr telephone set from said trunk,.when the trunk is connected to said outgoing line, means controlled from the A operators position when said iirst connection is broken thereat and a second connection is made with said trunk before a disconnection is made at the B operators position tor aga-in operating said signal and forro-connecting the operators telephone set to said trunk.

5. Inl a telephone exchange system, the combination of an A operators position and a B operators position, trunk lines extending between said positions, an individual signal for each' of said trunk lines and av telephone set at the B operators position, means at the B operators position for connecting said trunks to outgoing lines, a sipy nailing circuit common to said trunks exten( ing between said' positions, means for transmitting a signal over said common signalling circuit from the A tol the B operators position Jfor causing the4 operation of one of said signals and for connecting the telephone set to said trunk, when one of said trunk 

